Research On Key Technology Of Guidance Link Based On Video Guidance System

Video guidance use video webcam to get target image information and transfer the information to guidance site through uplink.According to the received image information,the person working at the guidance site will determine the accurate location where the target is and then send commands to control the missile to attack the target.In the uplink,fast transmission and real-time process are needed for giant image data.Due to wireless channel having relatively narrow bandwidth and complex interference,more requirements is proposed for the whole communication link.A feasible uplink solution(from getting image information to guidance site image retrieval)is proposed in this thesis.The key technology includes image data compression,channel coding,direct sequence spread spectrum(DSSS)and MSK modulation.wherein image compression will be blocked into some parts and each part will be done discrete cosine transform(DCT),and then quantified by JPEG luminance quantization matrix,finally processed with entropy coding.Comparing with multiple coding methods,entropy encoding select the combination of the differential coding and Huffman coding,which integrated the respective advantages of differential coding and Huffman coding to achieve a more ideal image compression ratio.There are few domestic studies of its kind to add channel coding,this thesis takes in the convolution coding and Viterbi decoding and the introduction of the error correcting code will provide a strong error correction for communication link function,can greatly reduce the channel bit error rate.In modem link,this thesis adopts the direct sequence spread spectrum technology,the technology with strong anti-multipath interference capability,good concealment,low probability of intercept,low error,is widely used in wireless communication field,at the same time through the minimum frequency shift keying MSK modulation spread spectrum signal,the technology will more adapt to the nonlinear characteristics of channels,and improve the spectrum utilization.At the end of this thesis,the feasibility of the system is discussed through MATLAB simulation results.Gaussian white noise and multi-sound interference areadded into the system,and from the perspective of the bit error rate,the reliability of the communication link is analyzed.The practice proved that this scheme can realize the image data compression with highly effective coding efficiency and strong anti-jamming capability.Especially for blocking interference,this scheme will showed excellent anti-jamming performance and satisfy the requirement of the video guidance weapon system.